A zoetrope produces the illusion of motion from a rapid succession of static pictures. A typical zoetrope employs a rotatable cylinder with vertical slits cut into its sides. A band including a series of images, which can be drawings or photographs, is placed within the cylinder to be viewed through the slits. The cylinder can then be rotated while the viewer looks through the slits at the images on the opposite side of the cylinder's interior.
As the viewer sees the images pass by an individual slit, the illusion of motion is perceived. This illusion of motion depends on two things: persistence of vision and the phi phenomenon. Persistence of vision derives from the length of time the retina, which basically forms a “screen” at the back of our eyes that receives light, retains an image. When a flash of light is perceived every tenth of a second or less, it is perceived as continuous. Each flash of light leaves an impression that persists in the retina for at least one-tenth of a second. Because of this persistence, the viewer cannot tell when one flash ends and the next begins thereby giving the perception of continuity. In a zoetrope, that persistence is achieved by viewing through the slots, which simulate flashes of light to the viewer in a stroboscopic effect. The other contributor to the illusion of motion, the Phi phenomenon, derives from the human instinct to create a relationship between images that are viewed in quick progression. The brain naturally seeks to merge the gaps between the progressive images to produce greater continuity of movement.
One knowledgeable in the field will be aware that persistence of vision and the Phi phenomenon have been exploited in numerous other applications. In one application, a flat disk with a cyclic series of images is placed on a record turntable, and an upstanding mirror arrangement with a number of facets corresponding to the number of images is centered on the turntable. With that, the turntable can be rotated, and the illusion of animation of the series of images is achieved as the viewer focuses on the mirror arrangement. A similar turntable arrangement is disclosed in U.S. Pat. No. 6,549,503, except that the mirror arrangement is replaced by a fixedly retained stroboscopic light and the images are perceived by a generally inactive operator through one or more “viewing ports.”
While very entertaining, such arrangements require a turntable, which is becoming a less and less common possession as vinyl records become increasingly rare. Moreover, the mirror arrangement employed previously, although attractive and entertaining, would be relatively expensive and complex to reproduce and is easily damaged and prone to malfunction. Still further, since the animation may be automatically produced, the user is entertained but may not be able to vary the character of the animation and to achieve the learning that derives therefrom. Even further, it will be seen that the animation devices of the prior art have left the user as an inactive observer who watches the animation phenomenon with no ability to impart much effect on the same other than to trigger its start or to re-energize its motion.